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2012-11-11debloat src/thread tree but putting lots of junk in one fileRich Felker-108/+93
POSIX includes mostly-useless attribute-get functions for each attribute-set function, presumably out of some object-oriented dogmatism. the get functions are not useful with the simple idiomatic usage of attributes. there are of course possible valid uses of them (like writing wrappers for pthread init functions that perform special actions on the presence of certain attributes), but considering how tiny these functions are anyway, little is lost by putting them all in one file, and some build-time cost and archive-file-size benefits are achieved.
2012-11-11report support of TPS option in unistd.h and sysconfRich Felker-2/+2
also update another newish feature in sysconf, stackaddr
2012-11-11add support for thread scheduling (POSIX TPS option)Rich Felker-13/+147
linux's sched_* syscalls actually implement the TPS (thread scheduling) functionality, not the PS (process scheduling) functionality which the sched_* functions are supposed to have. omitting support for the PS option (and having the sched_* interfaces fail with ENOSYS rather than omitting them, since some broken software assumes they exist) seems to be the only conforming way to do this on linux.
2012-11-11fix clobber of edx in i386 vsyscall asmRich Felker-1/+2
this function does not obey the normal calling convention; like a syscall instruction, it's expected not to clobber any registers except the return value. clobbering edx could break callers that were reusing the value cached in edx after the syscall returns.
2012-11-09always add memory streams to stdio open file listRich Felker-18/+21
per interpretation for austin group issue #626, fflush(0) and exit() must block waiting for a lock if another thread has locked a memory stream with flockfile. this adds some otherwise-unnecessary synchronization cost to use of memory streams, but there was already a synchronization cost calling malloc anyway. previously the stream was only added to the open file list in single-threaded programs, so that upon subsequent call to pthread_create, locking could be turned on for the stream.
2012-11-09support ldso path files without final newlineRich Felker-2/+5
2012-11-08change ldso path file logic to replace rather than add to search pathRich Felker-2/+2
this change was originally intended just to avoid repeated attempts to open a nonexistant /etc/ls-musl-$(ARCH).path file, but I realized it also prevents the default paths from being searched when such a path file exists. despite the potential to break existing usage, I believe the new behavior is the right behavior, and it's better to fix it sooner rather than later. with the old behavior, it was impossible to inhibit search of default paths which might contain musl-incompatible libs (or even libs from a different cpu arch, on multi-arch machines).
2012-11-08clean up sloppy nested inclusion from pthread_impl.hRich Felker-16/+28
this mirrors the stdio_impl.h cleanup. one header which is not strictly needed, errno.h, is left in pthread_impl.h, because since pthread functions return their error codes rather than using errno, nearly every single pthread function needs the errno constants. in a few places, rather than bringing in string.h to use memset, the memset was replaced by direct assignment. this seems to generate much better code anyway, and makes many functions which were previously non-leaf functions into leaf functions (possibly eliminating a great deal of bloat on some platforms where non-leaf functions require ugly prologue and/or epilogue).
2012-11-08clean up stdio_impl.hRich Felker-19/+93
this header evolved to facilitate the extremely lazy practice of omitting explicit includes of the necessary headers in individual stdio source files; not only was this sloppy, but it also increased build time. now, stdio_impl.h is only including the headers it needs for its own use; any further headers needed by source files are included directly where needed.
2012-11-08fix dlsym asm for mipsRich Felker-1/+2
saving the return address from the delay slot is not valid -- by the time the instruction executes, the return address has already been replaced.
2012-11-05improve SOCK_NONBLOCK/SOCK_CLOEXEC fallback codeRich Felker-1/+2
checking for EINVAL should be sufficient, but qemu user emulation returns EPROTONOSUPPORT in some of the failure cases, and it seems conceivable that other kernels doing linux-emulation could make the same mistake. since DNS lookups and other important code might break if the fallback does not get invoked, be extra careful and check for either error. note that it's important NOT to perform the fallback code on other errors such as resource-exhaustion cases, since the fallback is not atomic and will lead to file-descriptor leaks in multi-threaded programs that use exec. the fallback code is only "safe" to run when the initial failure is caused by the application's choice of arguments, not the system state.
2012-11-04mips cache flush/ctl syscall support and headerRich Felker-0/+18
2012-11-01remove one unnecessary static var from dynamic linkerRich Felker-2/+2
2012-11-01fix more unused variable warningsRich Felker-6/+5
some of these were coming from stdio functions locking files without unlocking them. I believe it's useful for this to throw a warning, so I added a new macro that's self-documenting that the file will never be unlocked to avoid the warning in the few places where it's wrong.
2012-11-01fix unused variable warningsRich Felker-2/+1
2012-10-31add dl_iterate_phdr interfaceRich Felker-7/+87
patches by Alex Caudill (npx). the dynamic-linked version is almost identical to the final submitted patch; I just added a couple missing lines for saving the phdr address when the dynamic linker is invoked directly to run a program, and removed a couple to avoid introducing another unnecessary type. the static-linked version is based on npx's draft. it could use some improvements which are contingent on the startup code saving some additional information for later use.
2012-10-28system is a cancellation pointRich Felker-0/+3
ideally, system would also be cancellable while running the external command, but I cannot find any way to make that work without either leaking zombie processes or introducing behavior that is far outside what the standard specifies. glibc handles cancellation by killing the child process with SIGKILL, but this could be unsafe in that it could leave the data being manipulated by the command in an inconsistent state.
2012-10-28fix shmdt syscall calling convention on old archsRich Felker-1/+1
2012-10-27separate getc/putc from fgetc/fputcRich Felker-6/+25
for conformance, two functions should not have the same address. a conforming program could use the addresses of getc and fgetc in ways that assume they are distinct. normally i would just use a wrapper, but these functions are so small and performance-critical that an extra layer of function call could make the one that's a wrapper nearly twice as slow, so I'm just duplicating the code instead.
2012-10-25use explicit visibility to optimize a few hot-path function callsRich Felker-11/+13
on x86 and some other archs, functions which make function calls which might go through a PLT incur a significant overhead cost loading the GOT register prior to making the call. this load is utterly useless in musl, since all calls are bound at library-creation time using -Bsymbolic-functions, but the compiler has no way of knowing this, and attempts to set the default visibility to protected have failed due to bugs in GCC and binutils. this commit simply manually assigns hidden/protected visibility, as appropriate, to a few internal-use-only functions which have many callers, or which have callers that are hot paths like getc/putc. it shaves about 5k off the i386 libc.so with -Os. many of the improvements are in syscall wrappers, where the benefit is just size and performance improvement is unmeasurable noise amid the syscall overhead. however, stdio may be measurably faster. if in the future there are toolchains that can do the same thing globally without introducing linking bugs, it might be worth considering removing these workarounds.
2012-10-24correct locking in stdio functions that tried to be lock-freeRich Felker-16/+36
these functions must behave as if they obtain the lock via flockfile to satisfy POSIX requirements. since another thread can provably hold the lock when they are called, they must wait to obtain the lock before they can return, even if the correct return value could be obtained without locking. in the case of fclose and freopen, failure to do so could cause correct (albeit obscure) programs to crash or otherwise misbehave; in the case of feof, ferror, and fwide, failure to obtain the lock could sometimes return incorrect results. in any case, having these functions proceed and return while another thread held the lock was wrong.
2012-10-24greatly improve freopen behaviorRich Felker-17/+41
1. don't open /dev/null just as a basis to copy flags; use shared __fmodeflags function to get the right file flags for the mode. 2. handle the case (probably invalid, but whatever) case where the original stream's file descriptor was closed; previously, the logic re-closed it. 3. accept the "e" mode flag for close-on-exec; update dup3 to fallback to using dup2 so we can simply call __dup3 instead of putting fallback logic in freopen itself.
2012-10-24remove useless failure-check from freopen (can't happen)Rich Felker-2/+2
2012-10-22simplify logic in stpcpy; avoid copying first aligned byte twiceRich Felker-4/+4
gcc seems to be generating identical or near-identical code for both versions, but the newer code is more expressive of what it's doing.
2012-10-21as an extension, have putenv("VAR") behave as unsetenv("VAR")Rich Felker-5/+5
the behavior of putenv is left undefined if the argument does not contain an equal sign, but traditional implementations behave this way and gnulib replaces putenv if it doesn't do this.
2012-10-21accept "nan(n-char-sequence)" in strtod/scanf functionsRich Felker-1/+19
this will prevent gnulib from wrapping our strtod to handle this useless feature.
2012-10-21fix copy/paste error in popen changes that broke signalsRich Felker-1/+1
signal mask was not being restored after fork, but instead blocked again.
2012-10-19support looking up thread-local objects with dlsymRich Felker-0/+6
2012-10-19fix breakage in dlsym for looking up RTLD_DEFAULT, etc.Rich Felker-2/+5
this was broken during the early dynamic-linked TLS commits, which rearranged some of the code for handling new relocation types.
2012-10-19fix usage of locks with vforkRich Felker-3/+4
__release_ptc() is only valid in the parent; if it's performed in the child, the lock will be unlocked early then double-unlocked later, corrupting the lock state.
2012-10-19fix crashes in static-linked multithreaded programs without TLSRich Felker-0/+2
2012-10-19fix order of syscall args for microblaze clone syscallRich Felker-3/+2
with this commit, based on testing with patches to qemu which are not yet upstream,
2012-10-18ensure microblaze __set_thread_area returns successRich Felker-1/+2
since it did not set the return-value register, the caller could wrongly interpret this as failure.
2012-10-18avoid raising spurious division-by-zero exception in printfRich Felker-1/+1
2012-10-18floating point environment/exceptions support for mipsRich Felker-0/+60
2012-10-18fix parent-memory-clobber in posix_spawn (environ)Rich Felker-9/+17
2012-10-18overhaul system() and popen() to use vfork; fix various related bugsRich Felker-56/+110
since we target systems without overcommit, special care should be taken that system() and popen(), like posix_spawn(), do not fail in processes whose commit charges are too high to allow ordinary forking. this in turn requires special precautions to ensure that the parent process's signal handlers do not end up running in the shared-memory child, where they could corrupt the state of the parent process. popen has also been updated to use pipe2, so it does not have a fd-leak race in multi-threaded programs. since pipe2 is missing on older kernels, (non-atomic) emulation has been added. some silly bugs in the old code should be gone too.
2012-10-18fix (hopefully; untested) completely broken/incomplete microblaze sigsetjmpRich Felker-3/+12
2012-10-17fix microblaze asm relocations for shared libcRich Felker-6/+6
only @PLT relocations are considered functions for purposes of -Bsymbolic-functions, so always use @PLT. it should not hurt in the static-linked case.
2012-10-15add memmem function (gnu extension)Rich Felker-0/+148
based on strstr. passes gnulib tests and a few quick checks of my own.
2012-10-15add support for TLS variant I, presently needed for arm and mipsRich Felker-6/+46
despite documentation that makes it sound a lot different, the only ABI-constraint difference between TLS variants II and I seems to be that variant II stores the initial TLS segment immediately below the thread pointer (i.e. the thread pointer points to the end of it) and variant I stores the initial TLS segment above the thread pointer, requiring the thread descriptor to be stored below. the actual value stored in the thread pointer register also tends to have per-arch random offsets applied to it for silly micro-optimization purposes. with these changes applied, TLS should be basically working on all supported archs except microblaze. I'm still working on getting the necessary information and a working toolchain that can build TLS binaries for microblaze, but in theory, static-linked programs with TLS and dynamic-linked programs where only the main executable uses TLS should already work on microblaze. alignment constraints have not yet been heavily tested, so it's possible that this code does not always align TLS segments correctly on archs that need TLS variant I.
2012-10-15block uid/gid changes during posix_spawnRich Felker-0/+10
usage of vfork creates a situation where a process of lower privilege may momentarily have write access to the memory of a process of higher privilege. consider the case of a multi-threaded suid program which is calling posix_spawn in one thread while another thread drops the elevated privileges then runs untrusted (relative to the elevated privilege) code as the original invoking user. this untrusted code can then potentially modify the data the child process will use before calling exec, for example changing the pathname or arguments that will be passed to exec. note that if vfork is implemented as fork, the lock will not be held until the child execs, but since memory is not shared it does not matter.
2012-10-14fix overlap of thread stacks with thread tls segmentsRich Felker-2/+1
2012-10-14fix main program TLS alignment for dynamic-linked programsRich Felker-6/+5
this change brings the behavior in line with the static-linked code, which seems to be correct.
2012-10-13workaround broken hidden-visibility handling in pccRich Felker-1/+1
with this change, pcc-built musl libc.so seems to work correctly. the problem is that pcc generates GOT lookups for external-linkage symbols even if they are hidden, rather than using GOT-relative addressing. the entire reason we're using hidden visibility on the __libc object is to make it accessible prior to relocations -- not to mention inexpensive to access. unfortunately, the workaround makes it even more expensive on pcc. when the pcc issue is fixed, an appropriate version test should be added so new pcc can use the much more efficient variant.
2012-10-13fix namespace clash (libc) in dynlink.cRich Felker-14/+13
this makes it so the #undef libc and __libc name are no longer needed, which were problematic because the "accessor function" mode for accessing the libc struct could not be used, breaking build on any compiler without (working) visibility.
2012-10-13remove dead code from dynamic linkerRich Felker-10/+0
2012-10-11comment possibly-confusing i386 vsyscall asmRich Felker-1/+13
2012-10-11avoid the thread-ptr-init behavior of sigaction when not installing handlerRich Felker-1/+2
this is necessary because posix_spawn calls sigaction after vfork, and if the thread pointer is not already initialized, initializing it in the child corrupts the parent process's state.
2012-10-11i386 vsyscall support (vdso-provided sysenter/syscall instruction based)Rich Felker-16/+62
this doubles the performance of the fastest syscalls on the atom I tested it on; improvement is reportedly much more dramatic on worst-case cpus. cannot be used for cancellable syscalls.